This invention relates to a method of manufacturing seals and in particular to a method of manufacturing leaf seals.
Leaf seals are well known as a means of sealing a clearance gap between two rotating components such as the shafts of a gas turbine engine or a rotatable shaft and the housing surrounding the shaft. They may also be used as static seals.
The shafts of a gas turbine engine rotate at extremely high speeds and are also exposed to hot pressurised gases. As such the seals and their manufacturing process are required to be of a high quality.
Leaf seals, also known as foil seals, comprises a number of thin, resilient but flexible strips packed densely together and aligned, at an angle to the shaft axis, in the sealing direction. One end of the strips or leafs, either the radially inner or outer ends, are held within a housing with their other ends resting on the shaft so that the strips extend across the seal gap. One such seal design is disclosed in EP 0,933,567. The resilient ships of leaves of the seal are axially stiff and do not bend in the axial sealing direction, hence being sometimes preferable to brush seals.
Leaf seals are normally manufactured by producing a number of individual leafs or strips and stacking them together, face to face, in a controlled manner and then arranging them in an appropriately sized ring. However it is difficult to manufacture these seals in quantity as the manufacture of individual leaves and then stacking in a controlled manner is time consuming and costly.
It is an aim of this invention, therefore, to provide an improved method of manufacture of leaf seals which also alleviates the aforementioned problems.
According to the present invention there is provided a method of manufacturing a leaf seal suitable for use within a clearance between two components comprising the steps of providing a strip of seal material, forming corrugations within said strip, feeding said strip into guide means, pressing said corrugated strip into said guide means by angled ram means such that the corrugations lie at an acute angle to the perpendicular axis, securing said corrugated strip in a seal carrier, and cutting the free ends of the corrugations thus forming angled leaves of a leaf seal.